Four years ago Mark Zuckerberg was just another geeky psychology
student at Harvard - now he's a paper billionaire who's often
compared to Bill Gates and Steve Jobs.

With his brainchild, Facebook, now valued at $US15 billion
($16.8 billion) after Microsoft purchased a 1.6 per cent stake in
the social networking site for $US240 million, the 23-year-old has
turned his dorm room hobby into a star of the second web boom.

With a 20 per cent stake in the company, Zuckerberg could
theoretically sell out now and walk away with a cool $US3
billion.

The valuation makes News Corp's $US580 million buyout of MySpace
in 2005 seem like chicken feed. Indeed, Zuckerberg is no doubt
thanking his lucky stars he turned down Yahoo's paltry $US1 billion
takeover offer last year.

With 49 million active users worldwide, Facebook is now
outgrowing MySpace, which has over 200 million worldwide members.
If Facebook's executives and investors are to be believed, the site
is growing at between 3 and 3.5 per cent a week and could overtake
MySpace in as little as nine months.

In countries like Australia, there is a raft of evidence - both
quantitative and anecdotal - suggesting people are deserting their
MySpace profiles en masse to join Zuckerberg's hipper hangout.

Traffic monitor Hitwise says MySpace's Australian market share
is shrinking while Facebook increased its share threefold in the 10
weeks to October 13.

Zuckerberg owes much of his success to Gates, and it's not only
because the Microsoft founder just tipped hundreds of millions into
Facebook's coffers. In an interview with Forbes magazine
last year, Zuckerberg said Gates, also a Harvard dropout, inspired
him to skip school to work on outside projects during a talk Gates
gave to one of his computer science classes in 2004.

"He really encouraged all of us to take time off school to work
on a project. That's a policy at Harvard - you can take as much
time off as you want," Zuckerberg said.

Born in 1984 to a Jewish-American family, Zuckerberg was raised
north of New York City in the exclusive suburb Dobbs Ferry,
Westchester County.

After enrolling at Harvard in 2002, Zuckerberg took a punt on
other web plays before launching Facebook with Harvard buddy Dustin
Moskovitz in February 2004.

Campus newspaper The Harvard Crimson reported how, in
November 2003, Zuckerberg was almost kicked out of university for
creating a Harvard clone of the Hot or Not? website, which allowed
fellow students to rate each other's attractiveness.

Zuckerberg was reprimanded by the Harvard University
Administrative Board, which accused him of hacking into a
university database to obtain the student photos he used on the
site, Facemash.com. It is not clear what disciplinary action was
eventually taken.

But Zuckerberg's college hijinks must seem like a distant memory
for the now battle-hardened chief executive, who commands an army
of 300 workers and presides over annual revenues of more than
$US100 million. Over the next year he plans to double his troupe of
programmers to around 700.

Time will tell if Zuckerberg, who likes to dress in jeans and
Adidas sandals, has what it takes to steer a multi-billion-dollar
ship like Facebook, which he initially envisioned as little more
than a networking tool for Harvard students.

"I didn't care about being a CEO and I never really have,"
Zuckerberg told Forbes. "I didn't even care about running a
company - I just wanted to build cool things."

The reclusive founder, who according to the Financial
Times lived in rented accommodation with a mattress on the
floor as recently as May, certainly isn't giving off any hints,
having avoided an onslaught of media questioning by skipping
today's landmark conference call announcing the Microsoft
investment.

Perhaps Zuckerberg now prefers to stay out of the limelight and
let his more experienced executive team do the talking, after he
fumbled through a presentation in front of around 750 programmers
earlier this year. Visibly sweating, he announced Facebook would
become an open platform and welcome applications from third-party
developers.

And it's not just his inexperience that's making Zuckerberg
nervous. Already, former Harvard classmates have come out of the
wood work to file legal action against him, claiming Zuckerberg
stole their social network idea when he helped them with a project
in 2003.

The federal lawsuit was filed by the founders of rival site
ConnectU, who accuse Zuckerberg of copyright infringement, fraud
and stealing trade secrets. The case is still before the courts and
ConnectU has asked Facebook be shut down.

But if it all goes pear-shaped, Zuckerberg can rest easy knowing
he's come a long way since 2006, when pundits scolded him for
turning down the offer of a lifetime from Yahoo.

As Zuckerberg himself often says, "if Facebook ever falls
through, I'll consider going back to Harvard".